Take the side cover off the transmission (4 bolts) and inspect the gears and the 2-3 synchronizer. Item number one is to make sure the transmission can shift internally before you start tinkering with linkage. If the gears are rusty or damaged, no amount of linkage manipulating is going to help. I have a few torque tube type 3 speeds stashed if you need to replace the transmission.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!